<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<style>
    .outer {
        height: 400px;
        position: relative;
    }
    .left {
        height: 100%;
        width: 200px;
        background-color: blue;
    }
    .right {
        position: absolute;
        right: 0;
        top: 0;
        bottom: 0;
        left: 200px;
        background-color: red;
    }
    .outer2 {
        position: relative;
        height: 100px;
    }
    .left2 {
        position: absolute;
        width: 200px;
        height: 100px;
        background: tomato;
    }
    .right2 {
        margin-left: 200px;
        height: 100%;
        background: gold;
    }
</style>
<body>
<div class="outer">
    <div class="left"></div>
    <div class="right"></div>
</div>
<div class="outer2">
    <div class="left2"></div>
    <div class="right2"></div>
</div>
</body>
</html>
